A lithotripsy workstation of this kind is known from EP-A-286 170. Therein, the X-ray source and the image pick-up device are mounted on a U-arm which encompasses the table top of the patient supporting device and which is pivotable about a horizontal axis extending perpendicularly to the longitudinal direction of the table top. The U-arm is journalled in a stand. The shockwave generator is arranged so that its focus is situated at the point of intersection between the axis and the central ray.
In the known device it is comparatively easy to position a patient so that the (renal) calculus to be crushed is situated in the focus of the shockwave generator. In a first position in which the central ray extends perpendicular the patient is positioned so that the calculus is projected exactly onto the marked center of the image pick-up device, e.g. an X-ray image intensifier. The calculus is then situated in the central ray, but may still be situated above or underneath the focus. Therefore, in a second position of the U-arm, in which the central ray extends obliquely, the table top is lifted or lowered until the calculus is again situated in the center of the image intensifier which can be made visible in the X-ray image by way of cross-hairs or the like. The calculus is then situated in the focus of the shockwave generator.
In order to achieve the necessary positioning accuracy, the mechanical stability of the U-arm and the stand supporting this arm must be high. Therefore, the U-arm and the stand have an expensive and heavy construction. Moreover, the U-arm impedes access to the patient at the side of the patient table device where the stand is situated.